Abstract
Low soil nutrient status may be the major limiting factor to forage production in rangelands of the Mendoza plains 4 years out of 10. We studied vegetation responses to annual applications of N and P on such rangelands. Fertilizer application rates were 0 or 25 N and 0 or 11 P (kg ha-1) in a factorial arrangement. Dry matter production of grasses and palatable shrubs and crude protein (CP) content of grasses were determined annually from 1996 to 1998. Experimental plots received rains of 189, 278, and 346 mm during the 3 study years compared to mean growing season rainfall of 258 mm. Forage production was increased by N+P fertilization only in 1998 (1,390 vs 980 kg ha-1, P 0.05), producing 16.5 kg forage kg-1 N applied. Crude protein concentration was increased by N fertilization in 1997 (6.3 vs 5.3%, P < 0.05) and N+P application increased in 1998 (6.8 vs 5.7%, P < 0.05). Nitrogen and P application increased seasonal rain-use efficiency when the rainfall exceeded 300 mm. In 1998, the increase of grass production per kg N applied with and without P was 18.4 and 12.4 kg, respectively. The break-even point between rain and nutrients as the main primary production determinant on sandy soils in the central Mendoza plains is around 400 mm year-1 instead of 300 mm in other arid lands of the world. The value of meat increment derived from the N fertilization, with and without P application (US 0.07 ha-1 year-1 kg-1 N) was lower than the fertilizer cost (US 0.87 kg-1 N). A 5-fold increase in forage yields would be required to offset the cost of fertilizer. Fertilizer application did not increase forage production enough to be profitable for cattle production at present fertilizer and meat prices.
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Claims 11
Claim · model-written summary
N plus P fertilization increased forage production only in 1998, from 980 to 1,390 kg ha-1.
Verbatim
e0“Forage production was increased by N+P fertilization only in 1998 (1,390 vs 980 kg ha-1, P 0.05)”
t0“Rangeland Production”
Claim · model-written summary
The 1998 N plus P application produced 16.5 kg forage per kg N applied.
Verbatim
e0“producing 16.5 kg forage kg-1 N applied”
t0“Rangeland Production”
Claim · model-written summary
Nitrogen fertilization increased grass crude protein concentration in 1997 from 5.3% to 6.3%.
Verbatim
e0“Crude protein concentration was increased by N fertilization in 1997 (6.3 vs 5.3%, P < 0.05)”
t0“Rangeland Production”
Claim · model-written summary
Nitrogen plus phosphorus increased grass crude protein concentration in 1998 from 5.7% to 6.8%.
Verbatim
e0“Crude protein concentration was increased by N fertilization in 1997 (6.3 vs 5.3%, P < 0.05) and N+P application increased in 1998 (6.8 vs 5.7%, P < 0.05)”
t0“Rangeland Production”
Claim · model-written summary
Nitrogen and phosphorus application increased seasonal rain-use efficiency when rainfall exceeded 300 mm.
- Taxon
- Rangelandt0
- Treatment
- Nitrogen and P applicatione0
- Outcome
- seasonal rain-use efficiencye0
- Direction
- increasede0
- Qualifier
- rainfall exceeded 300 mme0
Not reportedComparator
Verbatim
e0“Nitrogen and P application increased seasonal rain-use efficiency when the rainfall exceeded 300 mm”
t0“Rangeland Production”
Claim · model-written summary
In 1998 grass production per kg N applied increased by 18.4 kg with P.
Verbatim
e0“In 1998, the increase of grass production per kg N applied with and without P was 18.4 and 12.4 kg, respectively”
t0“Rangeland Production”
Claim · model-written summary
In 1998 grass production per kg N applied increased by 12.4 kg without P.
Verbatim
e0“In 1998, the increase of grass production per kg N applied with and without P was 18.4 and 12.4 kg, respectively”
t0“Rangeland Production”
Claim · model-written summary
The rain–nutrient break-even point for primary production on sandy soils of central Mendoza is around 400 mm year-1.
Verbatim
e0“The break-even point between rain and nutrients as the main primary production determinant on sandy soils in the central Mendoza plains is around 400 mm year-1 instead of 300 mm in other arid lands of the world”
t0“Rangeland Production”
Claim · model-written summary
The estimated meat value derived from nitrogen fertilization was below fertilizer cost.
Verbatim
e0“The value of meat increment derived from the N fertilization, with and without P application (US 0.07 ha-1 year-1 kg-1 N) was lower than the fertilizer cost (US 0.87 kg-1 N)”
t0“Rangeland Production”
Claim · model-written summary
A fivefold forage yield increase would be needed to cover fertilizer cost.
Verbatim
e0“A 5-fold increase in forage yields would be required to offset the cost of fertilizer”
t0“Rangeland Production”
Claim · model-written summary
At current fertilizer and meat prices, fertilization was not profitable for cattle production.
Verbatim
e0“Fertilizer application did not increase forage production enough to be profitable for cattle production at present fertilizer and meat prices”
t0“Rangeland Production”